The present invention relates in general to a system for securing communication links between a computer system and a terminal, and more particularly to a system for accessing a computer system through terminal lines over which passwords are transmitted.
Computer systems have been subject to a variety of computer risks. Passwords have been used to authenticate a terminal user. The use of passwords have been augmented by secondary security measures. Such systems have not met the security standards presently required by governmental institutions and similar organizations.
In the patent to Atalla, U.S. Pat. No. 4,288,659, an operator actuated a keyboard to produce personal identification number, machine identification number and sequence number. The data was processed by an encoding module and an initialization key code produced by the encoding module was stored in a storage register. The transmission authentication code was transmitted to a central processing unit. The central processing unit included a memory file. An encoding module associated with the central processing unit produced from the stored memory file a personal identification number, a machine identification number and a sequence number. A transmission authentication code was produced therefrom which was compared to the initially produced transmission authentication code. If the comparison were favorable, then the operator had access to the stored data.
In the patent to Check, Jr., U.S. Pat. No. 4,310,720, a communication link was established between a remote user and a computer through an access unit. The access unit generated a password and a number gas an access code. The access code was transmitted and compared with an access code generated by a computer access controller. Additionally, the access code and the number provided an encoding key which was compared with an encoding key generated by the computer access controller. A favorable comparison established the communication link between the remote user and the computer.